Lower Back Pain: Disc versus Facet Joint Origin

by Raymond Hall, DC

Lower Back Pain affects approximately 80% of the population at some point during their lifetimes.

In the past 31 years of my practice, I see the most common pain coming from either the intervertebral discs (the cushions between the vertebrae) or from the facet articulations. There are many other causes of low back pain but for this particular discussion, I’m going to limit it to these two factors.

Facet articulations are two small joints behind the spinal cord that control the motion of the spine. They are approximately .5” x .25” in diameter. The reason these two joints are affected in the production of lower back pain is that they are responsible for the movement of the lower back, similar to the struts on your car. Intervertebral discs are the primary shock absorbers–approximately 0.5″ in height–and interconnect the bodies of the vertebral segments. Therefore, it can be considered that the discs and the facets create a triad of joint complexes, resulting in the shock absorption and movement of the segments of the spine.

So many patients come to me believing that most of their pain is muscular in origin. I would say that the amount of pain that is simply coming from muscle–and not involving either the disc or the facets–is very rare, most likely comprising about 5% of the lower back pain cases I see. There are a myriad of other possibilities that can cause back pain including degenerative arthritis, but for today, I will focus on the primary difference of symptoms that comes from each of the above joints.

Facet Articulations: Pain and Relief

When it comes to the lower lumbar spine facet articulations, it is most common to see pain with extension of the lower back. This backward bending of the trunk loads the facet articulations and is usually consistent with the inflammatory response of the joint itself. The joint is made up of a synovial lining of the articular surfaces that is very capable of producing inflammation, also known as synovitis. If increased pressure within the joint already exists, extension of the back (e.g. a cobra-like position) places further pressure and it becomes very painful. The other consistent finding in this type of injury is that forward flexion usually relieves this condition. The reason being that forward flexion decompresses the facet articulations and therefore releases some of the pressure.

How does Disc Pain differ from Facet Joint Pain?

A disc tear or space-occupying protrusion will generally have nerve root irritation that sends pain signals down into the gluteal region, the hip region and/or down into the leg, ankle, or foot. It is rare to have a facet-type syndrome refer pain that can be tracked to a specific nerve root down into the lower extremities (although it can happen in more of a generalized pain pattern). That is the differentiating factor between the symptoms of a facet articulation and the intervertebral disc injury.

When we talk about disc injury, we are usually referring to a small tear in the outer annular fibers of the disc that results in one of the following: a bulge, a protrusion, or an extrusion of the disc particle. In simple terms, this means that we are trying to differentiate whether there is a small disc tear that might be producing some inflammatory response that needs to be healed, or whether there is a bulge or protrusion that may be developing a compromised window where the nerve is exiting.

Disc Injuries: The Different Types

The basic difference between a bulge and a protrusion is that a bulge is a circumferential out-pouching, whereby a protrusion is usually more specific and localized to one side or the other. An extrusion occurs when the inner portion of the disc, also known as the nucleus pulposus, extrudes outward and beyond the outer fibers of the disc itself. This can be analogized to toothpaste exiting outside the tube itself.

In addition, it is seen that in most disc injuries, forward flexion creates a significant increase in pain as there is more pressure exerted into the back of the disc where the corresponding nerve is exiting the spine. So, again to generalize, the difference between a facet-type syndrome and a disc-type syndrome is that disc injuries are very sensitive to forward flexion and rotation and facet injuries and synovitis are very sensitive to extension.

And finally, with aging comes a decrease in the fluid in the disc themselves that puts more pressure on the bones and articulations which oftentimes will result in bone spurs and other degenerative changes which oftentimes turn into spinal stenosis type symptoms. While there are many different factors that create lower back pain from referred pain from the organs to gallstones, to bladder issues, to infections, to less common metastatic disease from cancers…the two most common conditions that I see are facet articulation inflammatory responses and acute or chronic disc injuries–both which present with specific signs.

How We Can Help

As a multidisciplinary group here at Pacific Coast Sports Medicine, we can generally and clearly identify and treat most conditions without surgery. We will most likely take x-rays of your spine and certainly perform diagnostic evaluations that include orthopedic analysis, neurological testing, digital palpation, muscle testing, range of motion analysis, and other forms of diagnostic evaluations. Oftentimes we also refer out to more specialized diagnostic evaluations such as MRIs and CT scans.

I hope this synopsis of lower back pain may help you better ascertain and understand the difference between facet injuries and/or disc injuries. You are more than welcome to come into our office for further evaluation and treatment. Also, please ask us about the mattresses that we would recommend. We are continuing to promote a mattress line that I have designed called JUST SLEEP beds in which optimal support and comfort are created in a mattress that can be shipped directly to your door, directly from the manufacturer for approximately one third the cost. We certainly would entertain more questions and would love to have you inquire at our front desk for more information.

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